| Active-Twist Rotor Control Applications for UAVs |
DEC 2004 |
9 pages |
| Authors:
Matthew L. Wilbur; W. K. Wilkie; ARMY RESEARCH LAB HAMPTON VA VEHICLE STRUCTURES DIRECTORATE
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 | The current state-of-the-art in active-twist rotor control is discussed using representative examples from analytical and experimental studies, and the application to rotary-wing UAVs is considered. Topics include vibration and noise reduction, rotor performance improvement, active blade tracking, stability augmentation, and rotor blade de-icing. A review of the current status of piezoelectric fiber composite actuator technology, the class of piezoelectric actuators implemented in active-twist rotor systems, is included. |
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| Wind Tunnel Evaluation of a Model Helicopter Main-Rotor Blade With Slotted Airfoils at the Tip |
DEC 2001 |
132 pages |
| Authors:
Kevin W. Noonan; William T. Yeager Jr.; Jeffrey D. Singleton; Matthew L. Wilbur; Paul H. Mirick; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
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| Data for rotors using unconventional airfoils are of interest to permit an evaluation of this technology's capability to meet the U.S. Army's need for increased helicopter mission effectiveness and improved safety and survivability. Thus, an experimental investigation was conducted in the Langley Transonic Dynamics Tunnel (TDT) to evaluate the effect of using slotted airfoils in the rotor blade tip region (85 to 100 percent radius) on rotor aerodynamic performance and ... |
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| Performance and Vibratory Loads Data from a Wind-Tunnel Test of a Model Helicopter Main-Rotor Blade with a Paddle-Type Tip |
MAY 1997 |
26 pages |
| Authors:
William T. Yeager Jr.; Kevin W. Noonan; Jeffrey D. Singleton; Matthew L. Wilbur; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
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| An investigation was conducted in the Langley Transonic Dynamics Tunnel to obtain data to permit evaluation of paddle-type tip technology for possible use in future U.S. advanced rotor designs. Data were obtained for both a baseline main-rotor blade and a main-rotor blade with a paddle-type tip. The baseline and paddle-type tip blades were compared with regard to rotor performance oscillatory pitch-link loads and 4-per-rev vertical fixed-system loads. Data were obtained ... |
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| An Experimental Study of the Sensitivity of Helicopter Rotor Blade Tracking to Root Pitch Adjustment in Hover |
DEC 91 |
14 pages |
| Authors:
W. K. Wilkie; Chester W. Langston; Paul H. Mirick; Jeffrey D. Singleton; Matthew L. Wilbur; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CEN TER
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| The sensitivity of blade tracking in hover to variations in root pitch was examined for two rotor configurations. Tests were conducted using a four-bladed articulated rotor mounted on the NASA-Army aeroelastic rotor experimental system (ARES). Two rotor configurations were tested: one consisting of a blade set with flexible fiberglass spars and one with stiffer (by a factor of five in flapwise and torsional stiffnesses) aluminum spars. Both blade sets were ... |
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| Application of PC Based, Real-Time, Data-Acquisition System in Rotorcraft Wind-Tunnel Testing |
JUL 89 |
26 pages |
| Authors:
Matthew L. Wilbur; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CEN TER
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| Data have been acquired for a rotorcraft test in the Langley Transonic Dynamics Tunnel using a desktop-data acquisition system. The system, which consists of an IBM Personal Computer AT (PC-AT) and an Omega Engineering OM-900 stand-alone interface system, is well suited for acquiring high-speed data on a limited number of channels. The data-acquisition system and the interrupt -driven software, which provides the capability for near real-time, cyclic data acquisition as ... |
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| Reduction of Blade-Vortex Interaction Noise Using Higher Harmonic Pitch Control |
JUL 89 |
19 pages |
| Authors:
Thomas F. Brooks; Earl R. Booth Jr.; J. R. Jolly Jr.; William T. Yeager Jr.; Matthew L. Wilbur; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CEN TER
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| An acoustics test using an aeroelastically scaled rotor was conducted to examine the effectiveness of higher harmonic blade pitch control for the reduction of impulsive blade-vortex interaction (BVI) noise. A four-bladed, 110 in. diameter, articulated rotor model was tested in a heavy gas (Freon-12) medium in the Transonic Dynamics Tunnel. Noise and vibration measurements were made for a range of matched flight conditions, where prescribed (open-loop) higher harmonic pitch was ... |
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| Wind-Tunnel Evaluation of an Advanced Main-Rotor Blade Design for a Utility-Class Helicopter |
SEP 87 |
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| Authors:
William T. Yeager Jr.; Wayne R. Mantay; Matthew L. Wilbur; Robert G. Cramer Jr.; Jeffrey D. Singleton; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
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 | An investigation was conducted in the Langley Transonic Dynamics Tunnel to evaluate differences between an existing utility-class main-rotor blade and an advanced-design main-rotor blade. The two rotor-blade designs were compared with regard to rotor performance, oscillatory pitch-link loads, and 4- per-rev vertical fixed-system loads. Tests were conducted in hover and over a range of simulated full-scale gross weights and density altitude conditions at advance ratios from 0.15 to 0.40. Results ... |
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